Unexpectedly Inadequate Image Circle: Schneider Angulon 65/5.6 on 6x17

Snowfire · Jun 30, 2021

Having recently come into possession of an old 6x17 rig, I set about acquiring a lens to use with it. As I wanted images to be properly panoramic, I wanted a wide-angle lens, and I tried to read up on the alternatives. One lens that seemed promising was the Schneider Angulon 65/5.6; one site listed its image circle as being in excess of 175mm, and the Malefic website clearly lists it as being one of the lenses that will cover 6x17:

https://www.maleficcameras.com/usable-lens

So I acquired one and fitted it to my camera. But I was in for a rude surprise:

The image circle I measure on this negative could charitably be said to be 165mm at maximum extent, and if one excludes degraded margins and clipped corners the practical number is more like 155mm (and worse if you try to mount a filter.) WTF?!

(and before you ask, there is nothing in the camera itself that could obviously truncate the image in this manner.)

I would dearly like to know how there could be such a discrepancy between what I read and what I observe. Are there multiple versions of this lens, and did I get the wrong one? It would be nice to know so I do not get burned like this in the future.

cramej · Jun 30, 2021

Does it matter if it's the MC vs non-MC version? I don't know. However, most image circle specs are at a certain aperture, usually f/16 or 22. If you were using something larger, the image circle would be smaller. If, in fact, the image circle is 175mm, that's just barely enough to cover and you would likely still have vignetting in the corners.

AgX · Jun 30, 2021

Snowfire said:
The image circle I measure on this negative could charitably be said to be 165mm at maximum extent, and if one excludes degraded margins and clipped corners the practical number is more like 155mm.

The nominal image circle for the Super-Angulon 5.6 is 170mm.
The Image circle for an Angulon 5.6 would be lesser. BUT a Angulon 5.6 seemingly did not exist, but only a 6.8.

Dan Fromm · Jun 30, 2021

OP, Schneider claims the 65/5.6 SA covers 135 mm @ f/5.6 and 170 mm @ f/22. 6x17's diagonal is 180 mm. I don't know what aperture you used when you took the shot, but you shouldn't expect the lens to cover 6x17 at any aperture.

You lost more image on the right side of the scan than on the left. Check that the lens is centered on the camera's gate.

Also, the scan you posted is horribly soft. Look at the negative. If it isn't sharp -- scans are sometimes softer than the image scanned -- you have a problem focusing or your lens has a problem.

Snowfire · Jun 30, 2021

Dan Fromm said:
.

You lost more image on the right side of the scan than on the left. Check that the lens is centered on the camera's gate.

Also, the scan you posted is horribly soft. Look at the negative. If it isn't sharp -- scans are sometimes softer than the image scanned -- you have a problem focusing or your lens has a problem.

-The scan was done in a hurry and is a bit off-center. I don't blame that on the camera. The gate boundaries are pretty hard to see on the film. I had to scan this in 3 passes with photomerge due to the limited carriage travel on my better scanner.

-The exposure was at f/11.

--Yes, the image is a tad out of focus, but it was just a practice shot and that is irrelevant to the matter at hand. The camera is quite challenging to focus, especially in bright light, as the focusing screen is on the dim side and in bright daylight only a tiny image patch at the center is actually visible even with the lens wide open.

I think we have established that this lens is not fit for the purpose at hand. The larger question is, where does one find reliable information on any lens so that this sort of experience can be avoided in the future?

Ian Grant · Jun 30, 2021

I use a pre MC black barrel 75mm f8 Super Angulon on my 617 and find it ideal, the 75mm is less common I also have an f5.6 version I use with my Wista 45DX. Th f8 version being smaller is fine with the 617 and scale focussing, or an external rangefinder. It's a standrad lens for the 6 and nice and wide for the 17.

Ideally you need a centre filter as the light fall off is noticeable, I was lucky to get a couple of brand new Hoya ND Centre Filters last year one was £55 and I think the other £70, they are made the same way as the Schneider and Rodenstock centre filters. Up until then I had been ahving to dodge both ends when printing and taking care that the long ends weren't under-exposed.

Ian

reddesert · Jun 30, 2021

- you have a Super Angulon 65/5.6 presumably. There is an older lens called an Angulon 65/6.8 that covers only 6x9. I mention this just to say that talking about "Schneider Angulon" will lead to confusion.

- the diagonal of 6x17cm is about 178-180mm. The lens may not be rated to cover 180mm at all, and if you want to cover 170mm you may need to stop down all the way to f/22. f/11 isn't far enough. At the extremes of coverage, there is usually a lot of vignetting of the aperture.

- trying to cover 178mm with a 65mm lens, you are asking the lens to have a coverage angle of almost 108 degrees. That means there is going to be a lot of light falloff. This is basically geometrical and only a little of it can be mitigated by lens design. So one has to either accept vignetting or enter the often complex and expensive world of center filters.

So it's not just about finding a reliable table of lens coverages, but understanding the challenges of extreme wide angles in rectilinear lenses. These challenges are moderated if, roughly speaking, you try to work with about 90 degrees of coverage, which means the lens focal length is half the diagonal of the film (that would be ~75mm on 4x5, or 90mm on 6x17).

BobD · Jun 30, 2021

If that shot were focused properly, I'd be quite pleased with it as it is (with a little cropping, of course).

AgX · Jun 30, 2021

Dan Fromm said:
OP, Schneider claims the 65/5.6 SA covers 135 mm @ f/5.6 and 170 mm @ f/22.

My Schneider data sheet states 170mm from f/16 onwards (so these data can be taken with a tiny bit of salt)

The problem though is that the OP has it about the Angulon, not the Super-Angulon. But I guess he just mixed them up.

Snowfire · Jun 30, 2021

The lens is in fact labeled Super-Angulon. Apologies if this point caused confusion.

vphill · Jun 30, 2021

Snowfire said:
The larger question is, where does one find reliable information on any lens so that this sort of experience can be avoided in the future?

I have always found this data sheet helpful in trying to figure out which lenses will cover a 6x17.

https://www.largeformatphotography.info/lenses/LF6x17cm.html

Snowfire · Jun 30, 2021

Thank you! That is exactly the kind of information I was seeking, more detailed than what I had. Knowing what I know now, a lens should probably have a nominal image circle of at least 195mm to be even marginally suitable, and preferably 210mm or greater to be comfortably usable at all apertures. That might put such lenses as the Grandagon 75/4.5 in play, but it looks like no 65mm lens is really going to cut it.The Schneider 72/5.6 is likely too rare and expensive for my purposes.

I am unused to the world of large-format lenses. In my 35mm kit, I have an old retrofocus rectilinear 14/2.8 which has a greater field of view (114 degrees) than any of these lenses and yet preserves reasonable register distance. Newer rectilinear lens designs by Laowa have fields of view as wide as 135 degrees. But it seems these designs have not filtered into the large-format world.

reddesert · Jul 1, 2021

Wide angle lenses for SLRs are retrofocus designs (of necessity to clear the mirror), and that also allows some mitigation of light falloff in ultra wides, for optics reasons that are kind of complicated to explain, including the location of the exit pupil. However, there is still a significant light falloff with any of the ultra wide lenses for purely geometrical reasons.

Retrofocus wide angles are often rather larger than non-retrofocus wides; you can see this by comparing a 28mm lens for a 35mm SLR to a 28mm lens for a 35mm rangefinder. That suggests scaling up an ultra wide retrofocus from 35mm to 6x17cm would be an incredibly large and expensive lens.

Large format has its own set of rationales for picture-making, and physical and optical constraints, and so ideas and equipment don't always scale that well from smaller formats.

AgX · Jul 1, 2021

Snowfire said:
I am unused to the world of large-format lenses.

Here the problem is that lenses of basically same name have been upgraded over the decades. That is why strict adherence to the designation is important in checking things out.

Dan Fromm · Jul 1, 2021

Snowfire said:
Thank you! That is exactly the kind of information I was seeking, more detailed than what I had. Knowing what I know now, a lens should probably have a nominal image circle of at least 195mm to be even marginally suitable, and preferably 210mm or greater to be comfortably usable at all apertures.

If you shoot with no movements 6x17 doesn't need lenses that cover more than 180 mm. As for coverage wide open, dream on. More exactly, stick to 35 mm and digital equivalents.

I am unused to the world of large-format lenses. In my 35mm kit, I have an old retrofocus rectilinear 14/2.8 which has a greater field of view (114 degrees) than any of these lenses and yet preserves reasonable register distance. Newer rectilinear lens designs by Laowa have fields of view as wide as 135 degrees. But it seems these designs have not filtered into the large-format world.

They're never going to. The LF market for ultra wide angle lenses is too small to support manufacture. If you want a rectilinear lens with high coverage, look for a Berthiot Perigraphe Ser. VIa. These open to f/14, are not to be confused with the Ser. VIb which open to f/6.8. Short ones can't be put in shutter, have to be front-mounted or used with a behind-the-lens shutter. Neither approach is easy or inexpensive.

Snowfire · Jul 1, 2021

Yes, that Berthiot 60/14 looks like a barrel lens, and those are a real pain to deal with---If I had one of those old Crown Graphics with a focal-plane shutter it would be a fun thing to play with, but otherwise impractical, not to mention the price.

In the real world, the most likely solution for me looks like either the aforementioned Grandagon or one of the 75mm Nikkors---they should at least be adequate stopped down, though I doubt I will be able to do shifts with them. But there is a Photoshop remedy for that, after all. In the mean time, I have ordered a $15 pinhole plate that can be taped to the lens board--I can shoot pinhole pictures just like a Holga! It might be amusing to play with.

I am aware that all rectilinear optics (even pinholes) suffer from cosine falloff. It is most glaringly obvious with short wide angle lenses, but it can even be detected on long lenses if you look closely enough. It seems that some photographers seek to mitigate this by using bespoke radial ND filters, but I see problems with this approach: first, there is no way they can be accurate at all apertures; second, if you are doing anything that otherwise calls for a filter (such as basic b&w photography) you are stuck with stacking filters, which would be a sketchy thing to attempt with wide-angle optics. Perhaps Photoshop is a better approach to this issue, too.

BrianShaw · Jul 1, 2021

Snowfire said:
Crown Graphics with a focal-plane shutter

Not intending to bust your chops, but another nomenclature issue. With BBC a focal plane shutter that would be a SPEED, not Crown. And, yes, a focal plane shutter is worth having since there are some interesting barrel lenses! That barrel lens, interesting but…

Dan Fromm · Jul 1, 2021

Snowfire said:
Yes, that Berthiot 60/14 looks like a barrel lens, and those are a real pain to deal with---If I had one of those old Crown Graphics with a focal-plane shutter it would be a fun thing to play with, but otherwise impractical, not to mention the price.

In the real world, the most likely solution for me looks like either the aforementioned Grandagon or one of the 75mm Nikkors---they should at least be adequate stopped down, though I doubt I will be able to do shifts with them. But there is a Photoshop remedy for that, after all. In the mean time, I have ordered a $15 pinhole plate that can be taped to the lens board--I can shoot pinhole pictures just like a Holga! It might be amusing to play with.

I am aware that all rectilinear optics (even pinholes) suffer from cosine falloff. It is most glaringly obvious with short wide angle lenses, but it can even be detected on long lenses if you look closely enough. It seems that some photographers seek to mitigate this by using bespoke radial ND filters, but I see problems with this approach: first, there is no way they can be accurate at all apertures; second, if you are doing anything that otherwise calls for a filter (such as basic b&w photography) you are stuck with stacking filters, which would be a sketchy thing to attempt with wide-angle optics. Perhaps Photoshop is a better approach to this issue, too.

All theory, no practice.

snaefell · Jul 9, 2021

Ian Grant said:
Ideally you need a centre filter as the light fall off is noticeable, I was lucky to get a couple of brand new Hoya ND Centre Filters last year one was £55 and I think the other £70, they are made the same way as the Schneider and Rodenstock centre filters. Up until then I had been ahving to dodge both ends when printing and taking care that the long ends weren't under-exposed.

I use a 8/75 Super Angulon as well, nice and small lens. I haven't been successfull to find an original centre filter (or it was ways too expensive), can you tell me, which filters from Hoya you are using?

Ian Grant · Jul 9, 2021

Here's a scan of the center filter box/label. I had no idea Hoya/Tokina made them until I stumbled on them on Ebay, actually there were 3 listed by the sae camera shop, I bought the two I needed, the 3rd was more expensive but sold as well. They were new but obviously old stock, I have to use two adapter rings to use this one on the 75mm f8 SA but that compensates for the filter being slightly oversized as they move it forward as well.

I've never seen these in a Hoya filter catalogue, I did find a reference online on how they were made which was the same as the Rodenstock, Zeiss, and Schneider center filters. I;ve no idea what the original prices were, the shop price labels on the boxes say "Opened" and the 62mm £55 and the 77mm £105, however I paid £30 and £35 BIN on Ebay.

Ian

Unexpectedly Inadequate Image Circle: Schneider Angulon 65/5.6 on 6x17

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